When the metric system was first invented, mass and volume were tied to water, so that 1 kg was defined as the mass of 1 litre of water at STP , and a litre is a 10x10x10 cube. So 1cc of water had a mass of exactly 1 gram by definition.
This is no longer the definition used. Mass and length/distance are base units with their own definitions.
So I would expect that 1cc of water is still pretty close to a gram, but not precisely equal. Maybe a tiny bit more or a tiny bit less.
So what is the precise mass of exactly 1000 cc of water by current definitions?
(Googling doesn’t help. It produces 100s of pages telling me that 1 cc has a mass of 1g. I’m sure the answer is somewhere out there, but after spending half an hour searching fruitlessly, I came here.)
It’s not just deuterium – there are isotopes of oxygen, as well (ax the site DPRK cites makes clear). I’m sensitive to these things because my thesis work was on energy transfer among vibrational modes of cyanide ions, and there are four chief types of cyanide, depending upon the isotopes of carbon and nitrogen. It made a big difference in the spectra, because the masses affected the vibration frequencies.
Temperature has a bigger effect than any isotopic concerns. As the temperature rises, the density decreases, down to about 0.960 g/cm3 just before it boils (at 1 atm pressure).
More on isotopes. The triple point of water depends on their proportions, and there’s some detail somewhere saying precise triple points must be measured using water averaged over “the seven seas”. Maybe this is from International Temperature Scale of 1990?
Note the OP isn’t asking for e.g. a conversion factor, but in effect for a prediction of an experimental result.
Sorry, my post was kind of insufficient. I didn’t assume you meant that knowingly or were thinking that specifically. My point was that “the original definition of 1cc = 1g” is an entirely different category from “the precise mass of exactly 1000 cc of water” which is no longer a thing “by current definitions”. It’s now a thing you can only measure, a thing that can no longer be asserted from definitions alone. There’s not an exact mass of 1000 cc of water. There are precision values, but they won’t match in all their digits and would be scattered according to experimental accuracy as well as definite known effects such as isotopic proportions, barometric pressure, purity, et cetera.
Looking at this as a purely mathematical exercise, is there a way to start with the assumption 1cc of water = 1g, use the redefinition of meter and kilogram to say that now 1cc of water = Xg?
To avoid going into the weeds on isotopes, pressure and temperature, &c. treat my question as if it were: Before the redefinition of SI values, 1cc of vibranium was 1g under all conditions. After the redefinition, 1 cc of vibranium is how many grams?
Interesting tidbit about the triple point of water: it was defined to be 273.16 K (0.01 °C) between 1948 and 2019. Since 2019, it is no longer a defined temperature.
